package unit11;

import java.util.Scanner;

public class Demo {
	public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
		System.out.println("请输入一个整数？");
		int x=in.nextInt();
		if(x<0)
			throw new IllegalArgumentException("x<0");
		double y=Math.sqrt(x);
		System.out.println(y);
	}
}
